1. Field of the Invention
The present invention relates to a rotary connector which electrically connects an electrical device provided in a steering wheel with an electrical device provided in a vehicle, and more particularly, to a structure of connecting a fixed-side housing with a movable-side housing.
2. Description of the Related Art
A conventional rotary connector has been known before (for example, Japanese Unexamined Patent Application Publication No. 2003-174715). As shown FIG. 5, the conventional rotary connector includes a fixed-side housing 103 that includes a cylindrical case 101 and a ring-shaped cover 102 for covering one end of the case 101; a movable-side housing 106 that includes a ring-shaped top panel part 104 for covering the other end of the case 101 and a first cylindrical part 105 rising downward from an inner circumferential end of the top panel part 104; a rotor snap 110 that includes a ring-shaped locking part 107 locked with an outer surface of the cover 102, a second cylindrical part 108 rising from an inner circumferential end of the locking part 107, and a third cylindrical part 109 connected to a steering wheel (not shown) joined with the second cylindrical part 108 so as to rotatably assemble the movable-side housing 106 to the fixed-side housing 103 by combining the first cylindrical part 105 with the second cylindrical part 108; a ring-shaped holder 111 that is received in ring-shaped space formed by assembling the movable-side housing 106 to the fixed-side housing 103; a roller 112 that is rotatably mounted on the ring-shaped holder 111; and a flexible cable 113 that is wound on the roller 112, and of which one end is connected to the movable-side housing 106 and the other end is connected to the fixed-side housing 103.
In the conventional rotary connector, an annular projection 114 formed on the upper side of an inner surface of the case 101 faces an annular recess 115 formed on a lower surface of the top panel part 104, and a lower surface of the cover 102 faces an upper surface of the locking part 107. For this reason, an axial position of the movable-side housing 106 with respect to the fixed-side housing 103 is regulated. Furthermore, the annular projection 114 is engaged with the annular recess 115, and a side surface of the locking part 107 faces a wall part 116 forming a step flexuously formed on an inner rim of the cover 102. For this reason, a radial position of the movable-side housing 106 with respect to the fixed-side housing 103 is regulated.
In this way, the movable-side housing 106 is rotatably supported on the fixed-side housing 103. In this case, if the fixed-side housing 103 is fixed to a stator part of a vehicle and the movable-side housing 106 is connected to a steering wheel, an electrical device provided in the steering wheel can be electrically connected to an electrical device provided in the vehicle through the flexible cable 113.
However, the conventional rotary connector has the following problems: Since the conventional rotary connector is formed by injection molding of insulating resin, it is difficult to accurately mold a portion, which is away from a rotation axis in a radial direction thereof, with resin. Moreover, since variation per hour causes large deformation, the annular projection 114 and the annular recess 115, which are away from a rotation axis in a radial direction and face each other, are in slide contact with each other during the rotation of the movable-side housing 106. Therefore, abnormal noise occurs.